JP3385002B2 - Optical inspection equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical inspection apparatus for inspecting a high-definition electronic circuit wiring pattern made of copper foil or the like on a circuit board in a non-contact manner. . 2. Description of the Related Art As a device for inspecting the continuity and short-circuit of a circuit of a printed circuit board formed by a well-known method such as exposure and etching at a high speed without damaging an object to be inspected, a non-inspection device is used. An optical inspection device that performs inspection by contact is used. In an optical inspection apparatus, a circuit pattern image on a printed circuit board is formed on a detection surface of a photodetector by an image detection optical system, and a defect in the circuit pattern is recognized and inspected from a detection signal of the photodetector. In such an optical inspection apparatus, one linear inspection area (hereinafter, referred to as “inspection area”) is formed on the surface of the inspection object.
An inspection line is set, and an optical image on the inspection line is detected by a line sensor. By moving the inspection line on the surface of the inspection object (hereinafter, referred to as scanning), the entire inspection object is inspected. In order to increase the resolving power at the time of detection, a method is adopted in which the inspection line is divided into a plurality of partial inspection lines, and an optical image of each partial inspection line is detected by each line sensor. FIG. 6 shows an example of a prior art of such an optical inspection apparatus. FIG. 6 is a perspective view showing a configuration of a main part of the conventional optical inspection apparatus. This prior art is shown in the Journal of the Japan Society of Precision Engineering, June 1993, pp. 129-136. In FIG. 6, four linear inspection lines L1, L2, L3 and L4 are set on a substrate 100 to be inspected placed on a moving stage 101. Inspection line L1
The optical image of L4 is the objective lens 104 and the reflecting prism 10
9, the respective CCD linear sensors 106A, 106A,
6B, 106C and 106D. The substrate to be inspected 100 is moved by the moving stage 101 to the inspection line L1.
To the inspection lines L1 to L4
4 by taking in the image signal of the image of
Inspect the 00 surface. Inspection lines L1 to L of substrate 100
In order to illuminate the vicinity of 4, the emission end 103 of the illumination fiber light source 102 is arranged in parallel to the inspection lines L1 to L4, and the substrate 100 is illuminated obliquely or vertically. When illuminating from the vertical direction, the optical path of the illumination light is changed by inserting a light beam splitter 105 into the optical path of the image detection optical system 104. A CCD linear sensor 106A, which is a one-dimensional charge-coupled device, is used to detect the images of the inspection lines L1 to L4.
To 106D are used. A standard product of a commercially available CCD linear sensor has a sensor chip length of 35 mm. Therefore, to detect a longer inspection line, the inspection line is divided and one CCD linear sensor is assigned to each divided inspection line. A normal CCD linear sensor has a package larger than an internal sensor chip. Accordingly, a plurality of CCD linear sensors 1 are arranged along one inspection line.
06A to 106D are arranged in one line, CC
An area between the sensor chips of the D linear sensors 106A to 106D cannot be detected. Therefore, in the above-described conventional technology, the inspection line is divided into four inspection lines L.
1, L2, L3 and L4. Inspection line L1
And L3 are on the same line, but the inspection lines L2 and L4
Are on the same other line as the inspection lines L1 and L3. Therefore, the inspection lines L1 and L2 are shifted by a predetermined distance in the Y direction. The reflected light from the inspection lines L1 and L3 passes through the objective lens 104 and is reflected by the surface 107A of the reflecting prism 107, and the CCD linear sensors 106A,
6B. Similarly, the reflected light from the inspection lines L2 and L4 is reflected by the surface 107B of the reflection prism 107, and the CCD linear sensors 106C and 106D
Incident on. [0005] In the conventional optical inspection apparatus, the positions of the inspection lines L1, L3 and the inspection lines L2, L4 are shifted in the Y direction. Therefore, when capturing the image data of the inspection object while moving the inspection object in the Y direction,
The image data of the inspection lines L1 and L3 and the inspection line L
Image data of inspection lines L2 and L4 at different positions from L1 and L3 are obtained at the same time. In order to generate an image of the entire circuit pattern based on the image data obtained from different positions in the Y direction in this way, a complicated position correction operation is required. In a generally used printed circuit board having a square shape of, for example, 500 mm in length and width, the circuit pattern is distorted by about 0.5 mm in some places due to expansion and contraction due to temperature and humidity, and thus slightly differs from the shape at the time of design. For this reason, the above-described position correction calculation is further complicated, and an error easily occurs in the inspection result. Furthermore, when the inspection line is further subdivided using a high magnification optical system to increase the resolution of detection,
The position correction calculation becomes extremely complicated, and the inspection speed is reduced and the inspection table is expensive. SUMMARY OF THE INVENTION An optical inspection apparatus according to the present invention comprises a single linear or band for scanning an inspection surface of an inspection object.
It was divided Jo inspection area into a plurality of portions of each partial inspection area
For capturing image data of to duplicate object optical images of the respective boundary, an angle of substantially 90 ° with pairs toward said each partial inspection area in a plane substantially parallel to said examination plane the first image sensor and a plurality arranged keeping linear
A first prism , a second prism, and a third prism disposed between the object to be inspected and the first image sensor and having a bottom surface of an isosceles triangle with a base angle of 45 °. In each of the prisms, two surfaces sandwiched by parallel equal sides are respectively referred to as a first main surface and a second main surface, and a surface sandwiched between parallel bottoms is referred to as a slope, a first major surface being bonded to the first major surface of the second prism, the second major surface of the second prism is joined to the first major surface of the third prism, the second main surface the specimen in the first prism opposite the first and the second main surface the object to be inspected of the third prism in the opposite direction, opposite to the first image sensor
An optical element having the same configuration as the first optical element,
A counterclockwise direction about the optical axis with respect to the first optical element;
At a position along the optical axis direction while being rotated 90 ° to
Provided between the inspection object and the first optical element,
The second principal surface of the third prism is in a direction opposite to the inspection object
In the second position, the second position is arranged in accordance with the optical image of the inspection area.
The second optical element, between said first optical <br/> optical element and the first image sensor and the second light facing the image sensor
An image forming lens disposed between the optical element and the second image sensor to form an optical image of the object on each image sensor. According to the optical inspection apparatus of the present invention, by rotating the optical image of each partial inspection area by 90 ° , the optical image of the object in one linear inspection area can be converted into the object of the plurality of partial inspection areas. It is separated into an optical image of an object and forms images at positions separated from each other. Each linear image sensor that detects an optical image at a position distant from each other is also disposed apart from each other. Therefore, even if the package of the linear image sensor is larger than the internal sensor chip, it does not hinder the arrangement of the linear image sensor. Do not give. 1
Since the linear inspection area is detected by a plurality of linear image sensors, a high-resolution inspection object can be inspected with high accuracy. [0010] In the optical inspection apparatus of the present invention, in addition to the above-described functions and effects, optical images of one linear inspection area are detected by a plurality of image sensors and are synthesized, so that high definition is achieved. It is possible to detect an accurate inspection object with high accuracy. According to the optical inspection apparatus of the present invention, in addition to the above-mentioned functions and effects, one linear inspection area is divided into a plurality of partial inspection areas, and an object of each partial inspection area is inspected. The optical images are rotated at substantially 90 ° to form images at positions separated from each other. Since the rotation angle of the optical image is 90 °, it is easy to manufacture the optical element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a main part of the optical inspection apparatus of the present invention. In FIG. 1, an inspection object 1 such as a printed wiring board is placed on an XY table 2 and moves in directions indicated by arrows X and Y. An inspection line 3 which is a linear inspection area is set on the inspection surface 1A of the inspection object 1, and an optical image of the object on the linear inspection line 3 is detected by a line sensor via an optical system described in detail later. .
The line sensor is an image sensor that obtains image data of a linear region of the inspection object. The linear inspection line 3 may be a band-like region having a certain width. In that case, as the line sensor, an image sensor in which a detection unit is provided with a plurality of rows of detection elements and which can detect a band-like region is used. When the inspection object 1 is moved in the direction of the arrow X by the XY table 2 with the inspection line 3 fixed at a fixed position, the inspection surface 1A of the inspection object 1 is scanned by the inspection line 3. The inspection line 3 is divided into a plurality of partial inspection lines. In FIG. 1, four partial inspection lines 3A, 3B, 3
C and 3D. Inspection line 3 on inspection surface 1A
Are illuminated to an appropriate illuminance by the illumination device 18.
When the inspected object 1 is a luminous body, no illumination device is required. The detection unit 35 faces the inspection surface 1A,
36 is arranged, and the inspection unit 35 is
The inspection unit 36 detects the objects on A and 3B, and the inspection unit 36 detects the objects on the partial inspection lines 3C and 3D. The detection units 10A and 10B in the detection unit 35 are shown in the perspective view of FIG. Each of the detection units 10A and 10B has optical elements 11A and 11B configured by combining optical prisms, objective lenses 12A and 12B, and line sensors 13A and 13B. In FIG. 2, a mechanism for supporting each element is not shown for easy understanding of the configuration. Since the detection unit of the detection unit 36 has exactly the same configuration as the detection units 10A and 10B, only the detection unit 35 will be described in detail below. In FIG. 2, optical elements 11A and 11B
Has the same configuration, and the optical element 11B is
Is rotated by 90 ° counterclockwise around the optical axis Z. FIG. 3 shows that the optical element 11A, the partial inspection line 3A, and the line sensor 13A of FIG. 2 are rotated about 30 degrees counterclockwise around the optical axis Z so that the configuration of the optical element 11A can be easily understood. FIG. The optical element in this state is called an optical element 30. The optical element 30 is composed of triangular prisms 31, 32, and 33 having an isosceles triangular base with a base angle of 45 °. Note that the base angles of the prisms 31 to 33 are not limited to 45 °. Prisms 31, 32 and 33 all have the same shape and dimensions. In the prisms 31, 32, 33,
The two orthogonal surfaces sandwiched by the parallel equal sides are respectively a first main surface 31A, 32A, 33A and a second main surface 31B,
32B and 33B. Also, the surfaces sandwiched between the parallel bottoms are referred to as slopes 31C, 32C, and 33C, respectively. The first main surface 31A of the prism 31 is the first main surface 3 of the prism 32.
2A. Second principal surface 32B of prism 32
Is joined to the first main surface 33A of the prism 33. The second main surface 31B of the prism 31 is made to face the partial inspection line 3A of the inspection object, and the second main surface 33B of the prism 33 is made to face the line sensor 13A located in the direction opposite to the partial inspection line 3A. ing. The imaging lens 12A is placed between the prism 33 and the line sensor 13A. An object 20 on the partial inspection line 3A is indicated by an arrow, and a process of forming an optical image 26A on the line sensor 13A will be described. The reflected light of the object 20 illuminated with the appropriate illumination light enters the second main surface 31B of the prism 31 and is reflected on the inclined surface 31C as shown by the arrow 22. Slope 3
The reflected light from 1C enters the first main surface 32A of the prism 32 from the first main surface 31A, and is reflected on the inclined surface 32C as indicated by an arrow 23. The reflected light from the slope 32C is reflected on the second main surface 31B.
Incident on the first main surface 33A of the prism 33 from the
At C, the light is reflected as indicated by an arrow 24. The light reflected as indicated by the arrow 24 exits from the second main surface 33B and is formed by the imaging optical system 12A.
And form an image on the line sensor 13A to form an optical image 26A. Comparing the optical image 26A with the object 20,
At both spatial positions, the optical image 26A is rotated clockwise by 90 ° with respect to the object 20. Similarly, in the detecting section 10B of FIG. 2, the optical image 26B
It is rotated 0 °. As a result, the partial inspection lines 3A, 3A
The optical images of the object on B are rotated 90 ° clockwise and counterclockwise, respectively, to become optical images 26A and 26B. Similarly, the optical images 26A and 26A
Optical images 26C and 26D similar to B are obtained. As a result, the partial inspection line 3A obtained by the detection units 35 and 36
3D optical images 26A to 26D are as shown in plan views of the line sensors 13A to 13D shown in FIG. That is, the optical images of the partial inspection lines 3A to 3D obtained by dividing the straight inspection line 3 shown in FIG. 1 into four parts are converted into four parallel optical images 26A to 26D as shown in FIG. Each optical image 2
6A to 26D are located apart from each other, and by arranging the line sensors 13A to 13D in accordance with the respective optical images 26A to 26D, each optical image can be detected. Since the optical images 26A to 26D are separated from each other, the arrangement of the line sensors 13A to 13D does not hinder even if the package of the line sensor is considerably larger than the sensor chip. In the optical inspection apparatus of the specific example, for example, the object of the partial inspection line 3A and the objects of a part of the partial inspection line 3B adjacent to the partial inspection line 3A and a part of the partial inspection line 2D are included in the optical image 26A. It is desirable to design the imaging lens 12A so that an optical image of an object is included. This is the same for the optical images 26B, 26C and 26D. As described above, each partial inspection line 3A ~
By obtaining the image data in which the optical image of the 3D boundary portion is overlapped, the loss of the image data at the boundary portion can be prevented. The detection unit 35 and the detection unit 36 are preferably mounted on the respective bases, and the mounting and replacement of the detection units 35 and 36 are preferably performed for each base. In the above embodiment, the inspection line 3 is divided into four partial inspection lines 3A to 3D, but the number of divisions is not limited to four. It may be divided into a number of partial inspection lines of six or more. FIG. 5 is a circuit block diagram of the optical inspection apparatus of the present invention. In the figure, line sensors 13A to 13A
The image data of the optical images 26A to 26D detected in D is input to the image data storage circuit 41, and the image data obtained by scanning the entire surface of the inspection target substrate 1 is stored. The stored image data is input to the image data processing circuit 42, and the image data processing section 42 processes the overlapping image data at the boundary between the partial inspection lines 3A to 3D to generate image data in which the boundary of the inspection object is correctly continuous. The inspection object image forming circuit 43 generates image data of the entire surface of the inspection substrate 1. Image comparison circuit 4
In 5, the detected image of the substrate to be inspected is compared with a reference image stored in advance to detect a defect in the circuit and output it to the inspection result output circuit 46. In the present invention,
Partial inspection lines 3A to 3 obtained by dividing one linear area
Since the image data of the object on D is taken in at the same time,
The data processing of the image data processing circuit 42 is relatively simple. Therefore, the circuit scale of the image data processing circuit 42 can be made smaller than that of the prior art. Since the data processing is relatively simple, the processing speed is high and the time required for inspection is short. As described in detail in the above embodiments,
According to the present invention, the inspection line in one linear region is divided into a plurality of partial inspection lines, and the optical image of the object on each of the partial inspection lines is rotated by about 90 °. As a result, the optical images of the successive partial inspection lines are converted into a plurality of optical images that are separated and parallel to each other. Therefore, the optical image can be detected even by using a line sensor contained in a package which is considerably larger than the sensor chip. Further, since each partial inspection line is on one straight line, an error hardly occurs in comparison with the reference image.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an optical inspection apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of a detection unit according to an embodiment of the present invention. FIG. FIG. 4 is a plan view showing an optical image on a line sensor according to an embodiment of the present invention. FIG. 5 is a circuit block diagram of an optical inspection apparatus according to an embodiment of the present invention. FIG. 1 is an inspection object 1A inspection surface 2 XY table 3 inspection lines 3A, 3B, 3C, 3D partial inspection lines 10A, 10B inspection units 11A, 11B optical elements 12A, 12B Lens 13A, 13B, 13C, 13D Line sensor 18 Illumination device 26A, 26B, 26C, 26D Optical image 30 Optical element 31, 32, 33 Prism 31A, 32A, 33A First principal surface 31B, 32B , 33B Second principal surface 31C, 32C, 33C Slope 35, 36 Inspection unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01N 21/84-21/958 H01L 21/64-21/66 H01L 27 / 148 H01L 31/0232 H05K 3/00

Claims (1)

(57) [Claims 1] A single linear or band-shaped inspection area for scanning an inspection surface of an object to be inspected is divided into a plurality of parts, and the optics of each boundary part of each partial inspection area. for capturing image data of the overlap is allowed by the object image, substantially 90 ° to said pair toward each partial inspection area in a plane substantially parallel to said examination plane
Second angle of the plurality arranged while maintaining a linear first image sensor and a second image sensor, the disposed between the and the object to be inspected first image sensor, a base angle of 45 ° The prism includes a first prism , a second prism, and a third prism of a triangular prism having an equilateral triangular bottom surface. When the surface sandwiched between the parallel bases is called an inclined surface, the first main surface of the first prism is joined to the first main surface of the second prism, and the second main surface of the second prism is connected to the third prism. is bonded to the first major surface, a second major surface of the first prism faces the object to be inspected, the second main surface opposite direction to the inspection of the third prism, the first image sensor a first optical element which faces the same structure as the first optical element, the first Optics
90 ° counterclockwise rotation about the optical axis with respect to the element
The inspection object is positioned at a position along the optical axis direction
And a third prism provided between the first optical element and the first optical element.
The second main surface is in a direction opposite to the object to be inspected,
The second image sensor arranged in accordance with the optical image of the area
A second optical element facing the first optical element, between the first optical element and the first image sensor, and
Between the second optical element and the second image sensor.
Respectively are arranged, the optical inspection system having an imaging lens that forms an optical image of the object on each of the image sensors.